Lap sealable films

Abstract

A lap sealable film with superior film properties including a core layer of highly crystalline biaxially oriented polyester; first and second lap sealable non-crystalline or low-crystalline polyester layers each including substantially spherical particles and disposed onto opposite sides of the core layer. The first and second lap sealable polyester layers are adhered to the core layer.

1 . A film comprising: 
 a core layer comprising a polyester with a crystallinity value greater than 35%,    a first lap sealable layer on a first surface of the core layer comprising a polyester with a crystallinity value less than 35% and substantially spherical particles, and    a second lap sealable layer on a second surface of the core layer comprising a polyester with a crystallinity value less than 35% and substantially spherical particles.    
   
   
       2 . The film of  claim 1 , wherein the first and second lap sealable layers each have a thickness of 0.3 μm to 1.0 μm.  
   
   
       3 . The film of  claim 1 , wherein the thickness ratios of the of the first and second lap sealable layers to the core layers are about 1 to 6 to about 1 to 25.  
   
   
       4 . The film of  claim 1 , wherein the substantially spherical particles have an aspect ratio of less than 5.  
   
   
       5 . The film of  claim 1 , wherein the substantially spherical particles are silica particles.  
   
   
       6 . The film of  claim 1 , wherein the ratio of the mean spherical particle size of the substantially spherical particles to the thickness of the lap sealable film layer in which they are disposed is 4 to 1 to 2 to 1.  
   
   
       7 . The film of  claim 1 , wherein the substantially spherical particles have a mean particle size of 1 to 6 micrometers.  
   
   
       8 . The film of  claim 1 , wherein the first and second lap sealable layers comprise 0.2 wt. % to 0.5 wt. % substantially spherical particles.  
   
   
       9 . The film of  claim 1 , wherein the total thickness of the core layer and the first and second lap sealable layers is 5 μm to 60 μm.  
   
   
       10 . The film of  claim 1 , wherein the film has a static coefficient of friction to itself of less than 0.4.  
   
   
       11 . The film of  claim 1 , wherein the film has a haze % of 1% to 8%.  
   
   
       12 . A method for producing a film comprising: 
 co-extruding a core layer comprising a polyester with a crystallinity value greater than 35%, a first lap sealable layer on a first surface of the core layer comprising a polyester with a crystallinity value less than 35% and substantially spherical particles, and a second lap sealable layer on a second surface of the core layer comprising a polyester with a crystallinity value less than 35% and substantially spherical particles.    
   
   
       13 . The method of  claim 12 , further comprising biaxially stretching the film.  
   
   
       14 . The method of  claim 13 , further comprising heat setting the stretched film.  
   
   
       15 . The method of  claim 12 , wherein the first and second lap sealable layers each have a thickness of 0.3 μm to 1.0 μm.  
   
   
       16 . The method of  claim 12 , wherein the thickness ratios of the of the first and second lap sealable layers to the core layers are about 1 to 6 to about 1 to 25.  
   
   
       17 . The method of  claim 12 , wherein the substantially spherical particles have an aspect ratio of less than 5.  
   
   
       18 . The method of  claim 12 , wherein the substantially spherical particles are silica particles.  
   
   
       19 . The method of  claim 12 , wherein the ratio of the mean spherical particle size of the substantially spherical particles to the thickness of the lap sealable film layer in which they are disposed is 4 to 1 to 2 to 1.  
   
   
       20 . The method of  claim 12 , wherein the substantially spherical particles have a mean particle size of 1 to 6 micrometers.  
   
   
       21 . The method of  claim 12 , wherein the first and second lap sealable layers each comprise 0.2 wt. % to 0.5 wt. % substantially spherical particles.  
   
   
       22 . The method of  claim 12 , wherein the total thickness of the core layer and the first and second lap sealable layers is 5 μm to 60 μm.  
   
   
       23 . The method of  claim 12 , wherein the film has a static coefficient of friction to itself of less than 0.4.  
   
   
       24 . The method of  claim 12 , wherein the film has a haze % of 1% to 8%.